why won’t the hsv v scale go any higher than 1
Values in HSV nodes in both the Compositor and Shader Editor can go above 1:



1 means 100%. If we are talking about color information in an image 1 represents 100% of some color channel - the most it can be so it cannot go any higher, however color in Blender is 32bit so it can be pretty much any value. The dynamic range of colors can be a lot greater than it can be displayed in an image inside Blender. Colors of a render can be adjusted the way you want them to fit into an image - that's color grading. Anyway, you can definitely go above 100% or 1 in Blender in value of HSV nodes. It is not a good idea in some cases though as it might make your renders unrealistic.